In the absence of a rule specifying the calculation of tunnel radiation (from its walls and ceilings), the recommendation for simulating such situations is by creating a building to simulating such situations. which the same user must be characterised in terms of sound power and corrections applied. In other words, it is recommended to simulate only the emission at the entrance/exit but not the emission of the road along the tunnel.

If the stretch of road through the building is not removed, this section continues to emit and radiate outward, but the emission of that section is not considered reliable as it is very difficult to know exactly whatsoever. It should be recalled that CadnaA bases its calculations on external noise propagation standards.

Below is an example in which the road stretch is not removed from the tunnel (METMENDED METHOD):